The influence of tidal deformation and heating effects on a nearly
isolated gravitating systems due to external fields was successfully
treated and described by Booth and Creighton in [1]}.
Instead of using pseudotensorial techniques, which were more popular
at the time [2]}, [3]}, [4]},
the authors used the Brown-York quasilocal formalism to address the
problem. Specifically, in order to describe the interaction of a spatially
and temporally bounded gravitating system with an external tidal field,
they performed a variation of the boundary part of the total gravitational
Hamiltonian, which allowed them to calculate energy and momentum fluxes
on a quasilocal surface and thus determine the tidal work done by
an external gravitational field in the so-called 'buffer zone'. Taking
advantage of the fact that the associated quasilocal energy expression
coincides with the Arnowitt-Deser-Misner energy at spatial infinity
[5]}, [6]}, [7]}
and the Trautman-Bondi-Sachs energy at null infinity [8]}, [9]}, [10]}, [11]},
the authors provided two interesting applications of their formulae.
